function call() {
    $.ajax({
        url: 'http://192.168.21.210:8080/contact/select.php',
        type: 'post',
        success: win,
        error: nothing,
    });
};
call(); 

// error
function nothing() {
    console.log("网络出错!!!!");
};

// success
function win(msg){
    console.log(msg);
};